In general, an electronic induction heat cooking apparatus is an electric cooking apparatus for performing a cooking function by passing high-frequency current through a working coil or a heating coil and heating a cooking utensil by eddy current flowing when a strong line of magnetic force generated by the high-frequency current passes through the cooking utensil.
In the basic heating principle of the electronic induction heat cooking apparatus, the cooking utensil which is a magnetic body generates heat by induction heating as current is applied to a heating coil, and the cooking utensil itself is heated by the generated heat, thereby cooking food.
An inverter used for the electronic induction heat cooking apparatus serves to switch a voltage applied to the heating coil such that high-frequency current flows in the heating coil. The inverter drives a switching element generally composed of an insulated gate bipolar transistor (IGBT) such that high-frequency current flows in the heating coil, thereby forming a high-frequency magnetic field in the heating coil.
The power of the heating coil may be changed according to use of the heating coil. In general, a low-power heating coil and a high-power heating coil are formed and thus may be selectively used by a user according to purpose.
Meanwhile, if a three-phase voltage is applied, the power of the heating coil may be restricted to a predetermined value or less due to 1-phase allowed current restriction as in Europe. For example, when power of 3.7 kW or more cannot be output due to 1-phase allowed current restriction and high power of 5 kW or more is required, a dual heating coil having an inner coil and an outer coil is used.
FIG. 1 is a diagram illustrating heating of a cooking utensil using a dual coil in a conventional electronic induction heat cooking apparatus.
As shown in FIG. 1, the conventional electronic induction heat cooking apparatus includes an inner coil 41 and an outer coil 42 and a cooking utensil 50 is provided on the inner coils 41 and the outer coil 42.
The inner coil 41 may have a circular shape and the outer coil 42 may be provided outside the inner coil 41 and have a circular shape.
The electronic induction heat cooking apparatus may drive only the inner coil 41 of the dual heating coil according to the size of the cooking utensil 50 or user selection or drive the inner coil 41 and the outer coil 42 to heat the cooking utensil 50.
Meanwhile, if the dual heating coil is used, a two-phase voltage is used and two controllers are provided. In this case, since the oscillation frequencies of the controllers are different, the inner coil and the outer coil do not simultaneously operate, thereby reducing efficiency.